HIGH-STRENGTH STAINLESS STEEL FOR OIL WELL AND HIGH-STRENGTH STAINLESS STEEL PIPE FOR OIL WELL

• Main Authors: AMAYA, HISASHI, OTOME, YOHEI, TAKABE, HIDEKI, KONDO, KUNIO, OHE, TARO
• Format: Patent
• Language: English; French
• Published: 03.11.2011
• Subjects: ALLOYS; CHEMISTRY; FERROUS OR NON-FERROUS ALLOYS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; TREATMENT OF ALLOYS OR NON-FERROUS METALS

Disclosed is a high-strength stainless steel for oil wells having superior corrosion resistance in high temperature environments, having superior SSC resistance at normal temperatures, and having workability superior to 13% Cr steel. Specifically disclosed is a high-strength stainless steel for oil wells having a chemical composition that contains, in percent by mass, 0.05% or less C, 1.0% or less Si, 0.3% or less Mn, 0.05% or less P, less than 0.002% S, more than 16% and not more than 18% Cr, 1.5 - 3.0% Mo, 1.0 - 3.5% Cu, 3.5 - 6.5% Ni, 0.001 - 0.1% Al, 0.025% or less N, and 0.01% or less O, with the remainder being Fe and impurities. The high-strength stainless steel for oil wells also has a structure that includes a martensite phase, ferrite phase at a volume fraction of 10 - 48.5%, retained austenite phase at a volume fraction of 10% or less, yield strength of 758 MPa and uniform elongation of 10% or higher.